The present invention refers to an electroplating apparatus, consisting of a rod which links a vibrator to a basket, said vibrator comprising at least a baseplate, an electromagnet, a vibrating plate and a supporting device, said basket being connected to said rod by means of braces.
Such apparatuses are in principle already known in the electroplating industry. Small pieces to be electroplated are arranged in said basket, the basket is immersed into an electrolyte, and a direct electroplating current is established between the basket of the apparatus, connected as a cathode, and an appropriate anode outside the apparatus.
Known apparatuses of this kind, e.g. from U.S. Pat. No. 3,397,126 (Gilbert) or from SU-A-1 108 141, have two major drawbacks, one being their poor efficiency which decreases very quickly after a relatively short time of operation, and the other being their low reliability, these drawbacks being related to correct vibration.
The causes for this unsatisfactory operation of known apparatuses are at least four. The first problem concerns the air gap or interferric space between the pole pieces of the electromagnet which must be periodically adjusted. In known apparatuses having an intermediate plate between the electromagnet and the vibrating plate, this adjustment is delicate, time-consuming, and thus expensive. It requires disassembly of springs connecting the vibrating plate to the baseplate, and subsequent step-by-step adjustment of a stopper screw in a support member connecting the electromagnet to the baseplate. This adjustment is rendered even more delicate by the fact that the air gap between the pole pieces, normally about 0.35 mm, must be rigorously uniform. Consequently, the operator of the known devices must proceed by successive trials until the required uniformity is obtained. After the adjustment has been effected, the above-mentioned springs have to be reassembled.
The second problem lies in the transfer of the cathodic current. It is generally provided by a very small plug which is arranged beneath the vibrating plate and fitted in a member to which the conductive wires are connected. These conductive wires, the opposite ends of which are connected to the braces, extend in a hollow portion of the rod which links the vibrator to the basket and which accordingly has the form of a tube. It has been found that, on one hand, the current transmitting plug breaks easily when the basket has to be removed, e.g. in view of adjusting the air gap. On the other hand, the arrangement is such that it limits the fields of application considerably since the intensity of the cathode current should not exceed 10 A.
The third point contributing to the poor efficiency and impairing the reliability of the known apparatuses is the suspension device of the apparatus, i.e. a hook. Actually, transmission of the vibrations of the vibrator to the hook must be eliminated nearly totally. In the known devices, the hook is axially connected to the base plate.
Finally, the fourth problem of the known apparatuses concerns the tightness of the vibrator casing. In the known devices, the cover resp. the casing of the vibrator is made of aluminum. In particular, the casing is laterally screwed to an upper closing plate and to the base plate. However, redox processes are caused very quickly by the contact of the screws with the casing aluminum, and the resulting corrosion will impair the tightness of the casing.